The present invention relates to construction sanding blocks.
When using a sanding block, a flat piece of sandpaper is bent around the edges of a sanding block body. This results in waste of the sandpaper at the bent edges. In addition, after the surface is worn out, the sandpaper piece must be taken off the block and readjusted, but only, if there are any fresh portions available and if the flat piece of sandpaper still has adequate edges to be bent over the sanding block.
In contrast, when a mechanical sanding belt machine is used, a continuous loop sanding belt is applied over the sanding roller. However, this requires expensive sanding roller machines, which are not suitable for small detailed use by hand.
Among related patents for hand held sanding blocks include U.S. Pat. No. 3,414,036 of Gerhan and U.S. Pat. No. 5,387,251 of Rouse, which both show gear racks with teeth to tighten or loosen a sanding block.
U.S. Pat. No. 3,429,077 of Grover also uses teeth to tighten a hinged sanding belt block.
However, in Gerhan ""036, the sanding block includes two solid members, which must have teeth permanently attached therein or attached by a knob insertable within a hole in the body of the block. The length of the sanding block of Gerhan ""036 is adjusted by moving the two solid block bodies either away or toward each other. That requires disassembling and attaching the blocks to each other each time the length of the sanding block must be changed.
Moreover, both Rouse ""251 and Grover ""077 require a single pivotable hinged pin to be readjusted to different teeth of a gear rack. However, the pivoting pins in Rouse ""251 and Grover ""077 are more precariously held in place, and might cause injury to the user""s hand by suddenly slipping out of place.
Other patents which do not use gear racks for adjusting the length of a hand held sanding block include U.S. Pat. No. 2,761,257 of Mendelsohn, for a sanding belt block that uses springs, U.S. Pat. No. 6,213,857 of Duquette that uses an expanding wedge to tighten a sanding belt about the sanding block, U.S. Pat. No. 6,196,909 of Cadrobbi that moves a tension adjuster laterally to adjust the tension of the continuous sanding belt block, U.S. Pat. No. 3,975,868 of Botimer that holds sandpaper sheets with tucked-in edges and U.S. Pat. No. 4,525,959 of Ziebarth, that uses a wedge to tighten or loosen a sanding block tool.
Therefore there is a necessity to provide an adjustable sanding block which can hold a continuous loop sanding belt in place for convenient manual sanding of a surface, while maximizing the useful life of the sanding surface of the sanding belt.
It is also an object of the present invention to provide a reliable, accessible and easily insertable adjustment member which is inserted into a hollow body accommodating an endless sandpaper belt thereon, wherein the adjustment member adjusts the length of the sanding block.
Other objects which become apparent from the following description of the present invention.
In keeping with these objects and others, which may become apparent, the present invention includes a sanding block for holding a continuous loop sanding belt tightly thereon.
For the purposes of definition of the orientation of the sanding block, the xe2x80x9ctopxe2x80x9d and xe2x80x9cbottomxe2x80x9d of the sanding block is shown as providing access to the interior of the sanding block, and the front, rear and opposite sides of the sanding block are shown surrounding by an endless sanding belt. In such an orientation, the vertically extending sides of the sanding block can be used to sanding vertical surfaces, such as sheetrock walls.
However, also for the purpose of definition, it is noted that the sanding block can be rotated ninety degrees about its horizontal axis, so that the endless sanding belt is now facing up and down, for use in sanding horizontal surfaces, such as sheetrock ceilings or wooden floors.
It includes a hollow block body having a rack of serrated indented teeth extending longitudinally therein to form respective top and bottom gear racks.
The hollow block body is an open enclosure, which is open at an end thereof. The hollow block body preferably is rectangular with flat side walls. The spring clamp is inserted into the hollow block body through the open end for adjusting a length of the sanding block. The endless belt of sandpaper surrounds the hollow block.
Each of the gear racks engages reciprocal serrated indented teeth extending longitudinally along top and bottom forked members of a locking member, such as, for example, a spring clamp. The spring clamp member is insertable within the hollow block body and it extends a first predetermined length of the hollow block body to a longer length, so that the continuous loop sanding belt can be tightly fit over the hollow block body, as extended in length by a portion of the spring clamp extending from the hollow block body.
The teeth are provided along the inside of the top and bottom walls adjacent sides of each extended slot of the hollow block body. The teeth are adapted to engage the teeth on the top and bottom walls located on the extended arms of the spring clamp, so that the spring clamp, when inserted into the hollow block body, is held in place by the engagement of the teeth on the top and bottom walls of the hollow block body and the extended arms of the spring clamp;
Preferably, an optional button is provided on each of the distal ends of the extended arms of the spring clamp, and is accessible through the slots, allowing the extended arms to be pressed toward each other, to disengage the teeth, to allow the position of the spring clamp to be adjusted within the hollow block body.
The locking means is accessed through walls not covered by the endless belt, to allow tensing of the endless belt for sanding, and for release of tension, to allow the endless belt to be adjusted on the hollow block body, to provide a new sanding surface or replacement of the endless sanding belt.
Preferably, the spring clamp is a U-shaped member with outwardly extending arms, whose distal ends are biased away from each other, and a back edge joining proximal ends of the arms. The back edge of the U-shaped spring clamp extends out one end of the hollow block body, to contact the endless belt, for tensing or releasing tension on the endless belt.
These outwardly extending arms are toothed and these teeth engage the respective teeth of the interior of the hollow block body, to hold the adjusting spring clamp in place.
The hollow block body of the adjustable sanding block has openings for access to the toothed arms of the spring clamp, to allow adjustment of the position of the spring clamp or other adjusting means within the hollow block body. For example, the access opening may be extended slots in opposite walls of the hollow block body which are not covered by the endless belt.
The endless belt of sandpaper surrounds the hollow block body, and the endless belt extends along the side walls and ends of the hollow block body, wherein the back of the spring clamp is adjustable, to tense the endless belt for use in sanding. The spring clamp is retracted to allow the position of the endless belt on the hollow block body, to allow the endless belt to be changed and replaced.
When in use, the continuous loop sanding belt is taut, and provides a coarse or fine sanding surface over the hollow block body.